[PATCH] D86518: [RISC-V] fmv.s/fmv.d should be as cheap as a move

[Alexander Richardson via Phabricator via llvm-commits]

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Since the canonical floatig-point move is fsgnj rd, rs, rs, we should
handle this case in RISCVInstrInfo::isAsCheapAsAMove().


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D86518

Files:
  llvm/lib/Target/RISCV/RISCVInstrInfo.cpp


Index: llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -515,6 +515,11 @@
   switch (Opcode) {
   default:
     break;
+  case RISCV::FSGNJ_D:
+  case RISCV::FSGNJ_S:
+    // The canonical floatig-point move is fsgnj rd, rs, rs.
+    return MI.getOperand(1).isReg() && MI.getOperand(2).isReg() &&
+           MI.getOperand(1).getReg() == MI.getOperand(2).getReg();
   case RISCV::ADDI:
   case RISCV::ORI:
   case RISCV::XORI:


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